heta 97-0260-2716 avondale shipyards new orleans ... · building (shot house). company...

HETA 97-0260-2716Avondale Shipyards

New Orleans, Louisiana

Max KieferDoug Trout

Marjorie E. Wallace

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports



This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.


applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

http://www.cdc.gov/niosh/hhe/reports



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PREFACEThe Hazard Evaluations and Technical Assistance Branch of NIOSH conducts field investigations of possiblehealth hazards in the workplace. These investigations are conducted under the authority of Section 20(a)(6)of the Occupational Safety and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary ofHealth and Human Services, following a written request from any employer or authorized representative ofemployees, to determine whether any substance normally found in the place of employment has potentiallytoxic effects in such concentrations as used or found.

The Hazard Evaluations and Technical Assistance Branch also provides, upon request, technical andconsultative assistance to Federal, State, and local agencies; labor; industry; and other groups or individualsto control occupational health hazards and to prevent related trauma and disease. Mention of company namesor products does not constitute endorsement by the National Institute for Occupational Safety and Health.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORTThis report was prepared by Max Kiefer and Doug Trout of the Hazard Evaluations and Technical AssistanceBranch, Division of Surveillance, Hazard Evaluations and Field Studies (DSHEFS), and Marjorie E. Wallaceof the Engineering and Control Technology Branch, Division of Physical Sciences and Engineering. Fieldassistance was provided by Dave Sylvain, Janie Gittleman, and Sue Ting. Analytical support was providedby DPSE/ACS. Desktop publishing was performed by Pat Lovell and Nichole Herbert. Review andpreparation for printing was performed by Penny Arthur.

Copies of this report have been sent to employee and management representatives at Avondale and theOSHA Regional Office. This report is not copyrighted and may be freely reproduced. Single copies willbe available for a period of three years from the date of this report. To expedite your request, include aself–addressed mailing label along with your written request to:

NIOSH Publications Office4676 Columbia ParkwayCincinnati, Ohio 45226

800-356-4674

After this time, copies may be purchased from the National Technical Information Service (NTIS) at5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may beobtained from the NIOSH Publications Office at the Cincinnati address.

For the purpose of informing affected employees, copies of this report shall beposted by the employer in a prominent place accessible to the employees for aperiod of 30 calendar days.

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Health Hazard Evaluation Report 97-0260-2716Avondale ShipyardsAvondale, Louisiana

November 1998

Max KieferDoug Trout

Marjorie E. Wallace

SUMMARYOn July 9, 1997, the National Institute for Occupational Safety and Health (NIOSH) received a request from theMachinist Union, New Orleans Metal Trades Council, for a health hazard evaluation (HHE) at the AvondaleShipyards facility in Avondale, Louisiana. The request indicated that some shipyard employees have experiencedhealth problems possibly associated with workplace exposures. Potential exposures listed on the request were dustfrom sandblasting, welding fumes, contaminants from burning paint, and various solvents associated withfiberglass work. Reported health effects included breathing problems and nose bleeding.

On August 27, 1997, NIOSH investigators conducted an initial site visit at the Avondale Shipyard to review theprocesses and work practices in a large fabrication building referred to as the Factory and the abrasive blastingbuilding (Shot House). Company environmental monitoring data, the Avondale medical surveillance program forpersonnel in the arsenic and lead program, and company accident logs were reviewed. On October 22, 1997,personal breathing zone (PBZ) air sampling was conducted during the day shift to assess worker exposure towelding fume in the factory. Bulk samples of both new and recycled grit used in the Shot House were collectedto determine metal composition. During the night shift on October 22 and 23, PBZ samples were collected in theShot House to evaluate worker exposure to contaminants generated during abrasive blasting of ship parts.

Only passive general ventilation had been installed in the Factory. The highest measured welding fume particulateconcentration (55 milligrams per cubic meter [mg/m3]) was from a worker welding in a confined area (inside anInner Bottom Unit) for approximately 1.5 hours. NIOSH recommends controlling exposure to welding fume tothe lowest feasible concentration and meeting the exposure limit for each welding fume constituent. The other fourtime-weighted average (TWA) welding fume particulate concentrations ranged from 3.15 mg/m3 to 19.1 mg/m3.Measured lead concentrations in the Factory ranged from 0.003 mg/m3 to 0.010 mg/m3 and were all below theOccupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 0.05 mg/m3. Arsenicwas not detected in any of the samples collected in the Factory.

All workers evaluated in the Shot House wore supplied-air abrasive blasting respirators equipped with a vortextube for cooling. The Shot House decontamination trailer had a sound design and, if used properly, should helpreduce the potential for workers to “take home” contaminants such as lead. All measured exposures to iron andmanganese outside the workers’ abrasive blast hoods in the Shot House exceeded the NIOSH recommendedexposure limit (REL) (5.0 mg/m3 for iron, 1.0 mg/m3 for manganese). Except for one measurement that wasbetween the analytical limit of detection (LOD) and the limit of quantification (LOQ), all metal concentrationsfrom samples collected inside the abrasive blast hood were below NIOSH RELs. Assessment of respirator

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performance in the Shot House found that the abrasive blast hoods were performing well. The company’sbiological monitoring of workers in the Shot House includes measurement of total urinary arsenic; this alone is notan adequate method of assessing workplace arsenic exposure as it does not exclude non-toxic organic arseniccompounds found in seafood.

Air samples collected outside the abrasive blast hood in the Shot House contain large inertia-driven (rebound)abrasive grit particles. In samples collected during this evaluation, the large particles contributed over 95% of thetotal particulate, iron, and manganese content. Significant levels of lead or arsenic were not detected in the Factory.

The limited medical component of this HHE does not allow NIOSH investigators to draw conclusions concerningthe potential occupational exposures which could account for the respiratory complaints reported in the HHErequest. Concentrations of air contaminants (welding fume in the Factory, total particulate and metals in the ShotHouse) higher than those documented in our survey and/or improper use of respiratory protection among exposedworkers are factors that could potentially contribute to respiratory health effects among these workers. Weldingflash burns were the most commonly recorded injury in the Factory, and there is a need to ensure that appropriateshielding is used to reduce the potential for exposure, of both workers and others in the area, to the welding arc.

Monitored exposures to welding fume components exceeded applicable guidelines in the Factory; withone exception, respiratory protection worn by Factory welders was sufficiently protective. Measuredexposure during welding in a confined area, even when forced-air ventilation was provided, indicates thata higher level of respiratory protection is warranted until engineering or work practice controls areimplemented. The source of lead and arsenic contamination in the Shot House is likely the steel grit usedas the abrasive blasting agent. The controls in place during abrasive blasting appeared to adequatelyprotect workers. Current sampling methodology for abrasive blasting overestimates worker exposure tolead and other contaminants because non-inhalable abrasive grit enters the filter cassette. Sampling insidethe abrasive blast hood provides a more representative estimate of worker exposure. Recommendationsto help control exposure to welding fume in the Factory are provided in this report.

Keywords: SIC 3731 (Ship Building and Repairing). Abrasive blasting, air sampling, lead, arsenic, welding fume,ventilation.

TABLE OF CONTENTSPreface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Acknowledgments and Availability of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Shot House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Initial Site Visit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Follow-up Site Visit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Bulk Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Welding Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Industrial Hygiene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Workplace Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Air Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Shot House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Air Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Respirator Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Bulk Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Records Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Lead Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Welding in the Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Safety and Health Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Appendix A: Sampling and Analytical Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Bulk Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Appendix B: Control of Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Movable Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Fume Extraction Guns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Other Welding Fume Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Health Hazard Evaluation Report No. 97-0260-2716 Page 1

INTRODUCTIONIn response to a request for a health hazardevaluation (HHE) received on July 9, 1997, from theMachinist Union, New Orleans Metal TradesCouncil, the National Institute for OccupationalSafety and Health (NIOSH) conducted an initial sitevisit on August 27, 1997, and a follow-up survey onOctober 21-23, 1997, at the Avondale Shipyards inAvondale, Louisiana. Dust from sandblasting,welding fumes, contaminants from burning paint,and various solvents associated with fiberglass workwere potential exposures listed on the request.Health problems reported in the request includedbreathing problems and nose bleeds. An interimreport describing the actions taken by NIOSH duringthe initial site visit, and providing preliminaryfindings and recommendations, was issued onSeptember 23, 1997.

BACKGROUNDAvondale Shipyards encompasses approximately100 acres on the west bank of the Mississippi riveroutside of New Orleans, Louisiana. The shipyardhas been in operation for approximately 60 years andemploys 6000 workers. Most work is completed ontwo shifts (7:00 a.m. - 3:30 p.m., 3 p.m. - 11:00p.m.), with a “skeleton” crew working the 3rd shift(11:00 p.m. - 7:00 a.m.). The majority of the work atthe shipyard entails construction of naval vessels,with a smaller component engaged in commercialvessel construction. Although some ship repairoccurs, most of the work at the shipyard is newconstruction. The shipyard has two large floatingdry docks, various production shops and assemblyareas, machine shops, and engineering designcenters.

FactoryThe Factory is a 400,000 ft2 facility with fourproduction lines that add structural components toplate steel. Prior to the construction of the facility in1995, these activities were conducted outdoors

without covering. The building is equipped withlarge cranes and hydraulic lifts and has a ceilingheight of approximately 65 ft. The northeast side ofthe building is connected to the plate shop, and theother sides have large open panels. Only newconstruction occurs in this facility, with the majoractivities entailing welding and ship fitting. A red orgray water-based primer is applied to some of themetal components for anti-corrosion purposes. Noother painting or fiberglass work occurs in thefactory. Depending on the workload, there can befrom 350 to 500 workers over three shifts assigned tothe factory. The welders are not at fixed locationsand must frequently move about the work area.There are approximately 35 welding stations perproduction line. Welding operations occur in theFactory area where subsections, subassemblies, andunits are constructed.

Assembly advances through four separatedepartments referred to as Fabrication, Web, CPSU,and Unit. At the beginning of the process flow, largesteel plates are fabricated into parts for subsections.These subsections are then joined to fabricate alarger subassembly. At the final stage of the processflow, the subassemblies are combined to form largeunits. The units are then moved out of the Factory,inspected and blasted in the Shot House, and thentransported to be joined on board the ship. TheFactory produces approximately 18 units per week.As work progresses, the sections become morecomplex, and welding in confined areas occurs morefrequently.

The primary purpose of constructing the factory wasto provide shade and shelter from adverse weatherconditions. Only passive ventilation was designed inthe factory (ridge vent), and there are no existingprovisions for local or general mechanical exhaust.According to Avondale Safety and Healthdepartment personnel, welders utilize half-mask air-purifying respirators when working in open areas.For some specific welding activities (carbon arcprocess) in more confined areas, or when there is noforced air ventilation, employees are required to usesupplied air respirators. Reported employeeconcerns include the presence of a haze/smoke in the

Health Hazard Evaluation Report No. 97-0260-2716

factory from a build-up of welding emissions, andinadequate lighting during the night shifts.

To address employee concerns of exposure towelding emissions, Avondale contracted for anindustrial hygiene evaluation to assess general andpersonal exposures in the factory. The evaluationwas conducted over a six-month time frame toencompass seasonal changes. This survey found thatexposures to various welding-related contaminants(manganese, total particulate) exceeded permissibleexposure limits during certain welding tasks in semi-confined areas. As a result of this survey, Avondalesafety and health personnel have been investigatingproviding mechanical ventilation to reducecontaminant levels in the factory.

Shot HouseAfter the assembled ship parts leave the factory, theyare transported to the Blast and Paint building (ShotHouse) located on the north side of the factory.Approximately 50 employees work in this enclosedbuilding, where abrasive blasting is conducted on thesecond shift to remove the primer and prepare thesteel surfaces for painting. Steel shot, or grit,delivered from two blast pots on each side of theShot House is used as the blasting agent; dry blastingis utilized (no vacuum-assisted or wet blasting). Thebuilding is equipped with forced air ventilation anda dust collection system. A blast grit recoverysystem utilizing floor grates and a conveyor ispresent, where used shot is collected and thenseparated in the recovery system based on size (fineand coarse reject); grit meeting the size criteria isreused. Because of the complexity of the ship parts,workers must frequently conduct abrasive blasting inconfined areas.

As a result of a company industrial hygieneinvestigation that identified worker exposures to leadand arsenic exceeding Occupational Safety andHealth Administration (OSHA) permissibleexposure limits (PELs), the Shot House has beendesignated a regulated area as described in theOSHA comprehensive standards for lead (29 CFR1910.1025) and arsenic (29 CFR 1910.1018).

Because only new mild steel coated with water-based, “lead-free” primers undergo abrasive blastingin this facility, the presence of lead and arsenic wasan unexpected finding and the source had not beendetermined. Analysis of welding fume during theprocess step prior to abrasive blasting (FactoryAssembly) by Avondale did not identify the presenceof lead or arsenic. Personnel assigned to, or whomay have a need to work in this facility, participatein the lead and arsenic program. This programincludes exposure assessment (air sampling,biological monitoring), training, personal protectiveequipment (PPE), etc. A decontamination trailer(lockers, showers, “clean” and “dirty” side) has beeninstalled adjacent to the Shot House, and eachworker is provided two sets of clothing per day.Work clothing is laundered by a contractor.

METHODS

GeneralUpon receipt of the HHE request, additionalinformation regarding the reported health problemsand suspect environmental contaminants wasobtained from the requestor. Specific areas ofconcern identified by the HHE requestor were theFactory and the abrasive blasting operation.Discussions were held with Avondale safety andhealth personnel to obtain process and jobdescriptions for operations in these areas. Duringthese discussions, Avondale representativesindicated that additional ventilation controls andevaluation techniques were being considered forcertain activities involving the lead program.

Initial Site Visit

On August 27, 1997, NIOSH conducted an initialsite visit at the Avondale Shipyards facility. Thepurposes of this site visit were to identify areaswhere a NIOSH evaluation would be productive andto define the scope of any future activities. Toaccomplish this objective, efforts were focused onthe following:


C Company lead and arsenic program (medicalsurveillance, environmental monitoring,controls)

C (OSHA) Log and Summary of OccupationalInjuries and Illnesses (Form 200) for 1997

C Activities involving welding/torch cutting in theFactory

C Abrasive blasting activities and procedures

During this site visit, a walkthrough inspection wasconducted of the Factory, the Shot House, and thedecontamination facilities for personnel in the leadand arsenic program. Avondale representativesprovided an overview of the shipyard industrialhygiene and safety program and a copy of a reportfrom a recent (March 1995) comprehensive safetyand health program evaluation prepared by theOSHA Director of Maritime Standards.

Follow-up Site Visit

On October 21-23, 1997, NIOSH investigatorsconducted a follow-up site visit at the Avondalefacility. During this site visit, personal breathingzone (PBZ) air samples were collected to evaluateworker exposure to welding fume in the factory andcontaminants generated during abrasive blastingoperations in the Shot House. A detailed review ofwelding activities was conducted to betterunderstand the welding tasks in the factory and toallow NIOSH to offer specific ventilation or workpractice controls recommendations. PPE practiceswere also reviewed during this survey. Bulk samplesof both new and used abrasive blasting grit wereobtained for metal analysis. The biologicmonitoring results for employees participating inAvondale’s lead and arsenic exposure programs forthe period 1995 to the present were reviewed. Alongwith the biologic monitoring data, Avondale alsoprovided environmental sampling results for arsenicand lead performed in the Shot House.

Welding FumeFull-shift welding fume exposures were measured onfive welders during the first shift (7:00 a.m. - 3:30p.m.) on October 22. To prevent overloading,sample filter cassettes were replaced with new onesduring the lunch period. The morning samplingperiod ran from 7:00 a.m. - 12:00 p.m., and theafternoon sampling period was from 12:30 p.m. -3:30 p.m.. Two of the welders sampled worked onthe same unit in the Unit Department, one welderworked along Platen 20 in the CPSU Department,and one welder worked along Platen 40. A fifthwelder was sampled for part of the afternoon whilehe worked in a confined space (Inner Bottom) insideone of the units.

Abrasive BlastingPBZ air samples were collected from 11 abrasiveblasters during the second shift on October 22 and 23in the Shot House. For each abrasive blastermonitored, air samples were collected both insideand outside the abrasive blasting hood. Additionally,each abrasive blaster wore a “passive” monitor todetermine the extent of rebound, or inertia-driven,shot that entered the sampling cassette. The samplecollected outside the abrasive blaster’s hood, and thepassive sample, were further analyzed by removingthe larger size particulate fraction (loose bulk) fromthe filter cassette and analyzing this portionseparately. This monitoring strategy was employedto help determine the extent to which large (believedto be non-inhalable) particles of blasting materialsaffect the sampling results.

All PBZ samples (both welding and abrasiveblasting) were analyzed gravimetrically to determinethe total particulate concentration, and chemically, todetermine the concentration of the following metals:lead, arsenic, iron, manganese, copper, andchromium.


Bulk SamplesEight bulk samples of new and recycled shot werecollected in duplicate from the Shot House for metalanalysis to help determine the source of lead andarsenic previously detected in air samples collectedby Avondale. Steel grit samples were collected fromboth grit pots (north and south side) servicing theShot House, from the coarse and fine rejectcollectors, and from inside the Shot House floor. Allair samples were placed on hold until the bulksampling results became available, to ensure thatappropriate elemental analysis was conducted.

The analytical methodology used for the air and bulksamples is described in Appendix A.

EVALUATION CRITERIAAs a guide to the evaluation of the hazards posed byworkplace exposures, NIOSH field staff employenvironmental evaluation criteria for the assessmentof a number of chemical and physical agents. Thesecriteria are intended to suggest levels of exposure towhich most workers may be exposed up to 10 hoursper day, 40 hours per week for a working lifetimewithout experiencing adverse health effects. It is,however, important to note that not all workers willbe protected from adverse health effects even thoughtheir exposures are maintained below these levels. Asmall percentage may experience adverse healtheffects because of individual susceptibility, apre-existing medical condition, and/or ahypersensitivity (allergy). In addition, somehazardous substances may act in combination withother workplace exposures, the general environment,or with medications or personal habits of the workerto produce health effects even if the occupationalexposures are controlled at the level set by thecriterion. These combined effects are often notconsidered in the evaluation criteria. Also, somesubstances are absorbed by direct contact with theskin and mucous membranes, and thus potentiallyincrease the overall exposure. Finally, evaluationcriteria may change over the years as new

information on the toxic effects of an agent becomeavailable.

The primary sources of environmental evaluationcriteria for the workplace are: (1) NIOSHRecommended Exposure Limits (RELs)1, (2) theAmerican Conference of Governmental IndustrialHygienists' (ACGIH®) Threshold Limit Values(TLVs®)2, and (3) the U.S. Department of Labor,OSHA PELs3. In July 1992, the 11th Circuit Courtof Appeals vacated the 1989 OSHA PEL AirContaminants Standard. OSHA is currentlyenforcing the 1971 standards which are listed astransitional values in the current Code of FederalRegulations; however, some states operating theirown OSHA-approved job safety and healthprograms continue to enforce the 1989 limits.NIOSH encourages employers to follow the 1989OSHA limits, the NIOSH RELs, the ACGIH TLVs,or whichever are the more protective criterion. TheOSHA PELs reflect the feasibility of controllingexposures in various industries where the agents areused, whereas NIOSH RELs are based primarily onconcerns relating to the prevention of occupationaldisease. It should be noted when reviewing thisreport that employers are legally required to meetthose levels specified by an OSHA standard and thatthe OSHA PELs included in this report reflect the1971 values.

A time-weighted average (TWA) exposure refers tothe average airborne concentration of a substanceduring a normal 8- to 10-hour workday. Somesubstances have recommended short-term exposurelimits (STEL) or ceiling values which are intended tosupplement the TWA where there are recognizedtoxic effects from higher exposures over theshort-term.

Welding HazardsThe effect of welding fumes on an individual’shealth can vary depending on such factors as thelength and intensity of the exposure and the specificmetals involved. The content of welding fumesdepends on the base metal being welded, the weldingprocess and parameters (such as voltage and


amperage), the composition of the consumablewelding electrode or wire, the shielding gas, and anysurface coatings or contaminants on the base metal.It has been suggested that as much as 95% of thewelding fume actually originates from the melting ofthe electrode or wire.4 The flux coating (or core) ofthe electrode/wire may contain up to 30 organic andinorganic compounds. The primary purpose of theflux is to release a shielding gas to insulate the weldpuddle from air, thereby protecting againstoxidation.5 The size of welding fume particulate ishighly variable and ranges in diameter from less than1-micrometer (:m) (not visible) to 50-:m (seen assmoke).6

In general, welding fume constituents may includeminerals, such as silica and fluorides, and metals,such as arsenic, beryllium, cadmium, chromium,cobalt, nickel, copper, iron, lead, magnesium,manganese, molybdenum, tin, vanadium, andzinc.6,7,8 Low-carbon steel, or mild steel, isdistinguished from other steels by a carbon contentof less than 0.30%. This type of steel consistsmainly of iron, carbon, and manganese, but may alsocontain phosphorus, sulphur, and silicon. Most toxicmetals, such as nickel and chromium which arepresent in stainless steel, are not present in lowcarbon steel.

A PEL for total welding fumes has not beenestablished by OSHA; however, PELs have been setfor individual welding fume constituents (e.g., iron,manganese), and the PEL for total particulates nototherwise regulated is 15 milligrams per cubic meter(mg/m3) as an 8-hour TWA.9 The ACGIH hasestablished a TLV of 5 mg/m3 TWA for weldingfumes. The ACGIH suggests that “conclusionsbased on total fume concentration are generallyadequate if no toxic elements are present in thewelding rod, metal, or metal coating and ifconditions are not conducive to the formation oftoxic gases.”2 The ACGIH also recommends that arcwelding fumes be tested frequently to determinewhether exposure levels are exceeded for individualconstituents.2 NIOSH has concluded that it is notpossible to establish an exposure limit for totalwelding emissions since the composition of welding

fumes and gases vary greatly, and the weldingconstituents may interact to produce adverse healtheffects. Therefore, NIOSH recommends controllingtotal welding fume to the lowest feasibleconcentration (LFC) and meeting the exposure limitfor each welding fume constituent.10 The potentialhealth effects and NIOSH RELs for the metalsmeasured in the environmental samples during thissurvey are shown in the following table. Evaluationcriteria for lead and arsenic are presented separately.

Element NIOSH REL(mg/m3)

Principle Health Effects11

Chromium 0.5* skin and mucous membraneirritation, possible lung cancer

Iron 5 benign pneumoconiosis(siderosis)

Manganese 1 TWA3 STEL

central nervous system effects,pneumonitis, headaches

Copper 0.1 (fume)1 (dust/mist)

upper respiratory irritation,metal fume fever

* = Chromium can occur in various oxidation states. Certain hexavalentchromium compounds (chromic acid and chromates) have been shown tobe carcinogenic. NIOSH recommends controlling exposure to the LFC forthese compounds. Hexavalent chromium compounds have been detectedin stainless steel welding processes.7

In addition to welding particulate (known as fume),many other potential health hazards exist forwelders. Welding operations can produce gaseousemissions such as ozone, carbon monoxide, nitrogendioxide, and phosgene (formed from chlorinatedsolvent decomposition).6,7,8 Welders can also beexposed to hazardous levels of ultraviolet light fromthe welding arc if welding screens or otherprecautions are not used. Ergonomic problems arealso a consideration due to various contortedpositions welders assume for some welding tasks.

A detailed review of control options for reducingexposure to welding fume is provided inAppendix B.

Abrasive BlastingAbrasive blasting entails using pneumatic orhydraulic pressure or centrifugal force to direct a


blast of abrasive material (wet or dry) against asurface to clean, remove burrs, or develop a surfacefinish. Abrasive blasting is used in a variety ofindustries, and there are a wide variety of blastingtechniques, involving both handheld or automaticequipment.12 A large number of metallic and non-metallic abrasives are commonly used. Becauselarge quantities of dust are generated, abrasiveblasting is usually conducted in exhaustedenclosures, often equipped with air pollution controldevices and abrasive recycling systems. In theUnited States, the use of sand containing highconcentrations of free silica as an abrasive blastingagent continues to present a major hazard toworkers.12,13 Workers conducting abrasive blastingare exposed to both safety (rebound shot, highpressure, etc.) and health (high levels of dust fromabrasives and material being blasted) hazards, and anumber of precautions are necessary to ensureadequate protection. OSHA has establishedregulatory requirements for ventilation, enclosures,and PPE during abrasive blasting. Airlinerespirators specifically designed for abrasiveblasting (Type “CE” supplied-air) are required forwork inside of blast-cleaning rooms. Theserespirators are of rugged construction and equippedwith coverings to provide head, neck and upper bodyprotection from rebounding abrasive blastingmaterial.14

Assessing exposure during abrasive blasting forcompliance purposes requires collecting the sampleoutside the abrasive blast hood. These efforts tomonitor worker exposure during abrasive blastingwithin enclosures often result in measuringconcentrations far exceeding recommended limits.15

This is because of the high dust concentrationsgenerated in an abrasive blasting environment andthe potential for rebound shot to affect the samplingresults. The larger rebound shot enters the samplingcassette and, even though it is not “inhalable,”contributes, disproportionately, to the measured PBZexposure.

ArsenicArsenic is a naturally occurring element which canform a variety of inorganic and organic compounds,which have different toxicities. Various arseniccompounds are also found in some foods (e.g.,certain marine species may contain very highconcentrations of non-toxic organic arsenic).11,16,17

Most (68%) industrial use for arsenic is forpesticides (wood preservatives primarily). Otheruses include agricultural chemicals (23%), glass(4%) and non-ferrous alloy (3%) manufacturing.19

Arsenic is found in most fossil fuels and in cigarettesmoke. The natural arsenic content of soil variesbetween 0.1 and 80 parts per million, (ppm).17 Ingeneral, soluble inorganic arsenic compounds(arsenic combined with oxygen, chlorine, or sulfur)are considered to be the principal toxic species.Conversely, most organic arsenic compounds haverelatively low toxicity.17,18

Inorganic arsenic compounds may cause adversehealth effects following exposure via inhalation,ingestion, or dermal contact. Acute exposure toinorganic arsenic can cause nausea, vomiting,diarrhea, weakness, loss of appetite, cough, andheadache. Chronic exposure can result in weakness,nausea, vomiting, skin and eye irritation,hyperpigmentation, dermatitis, and numbness andweakness in the legs and feet.11 Peripheral vasculardisease ("Blackfoot disease") has been reported tooccur in association with chronic arsenic exposurefrom contaminated drinking water and among winemakers exposed to arsenical pesticides.17

There is clear evidence that chronic oral exposure toelevated levels of arsenic increases the risk of skincancer. Inhalation of certain arsenic compounds canalso result in lung cancer.17,18 NIOSH considersarsenic a potential occupational carcinogen,recommends controlling occupational exposures tothe lowest feasible concentration, and has establishedan REL of 2 micrograms per cubic meter (µg/m3) asa 15-minute ceiling limit.1


The OSHA arsenic standard (29 CFR 1910.1018)requires a medical surveillance program for workersexposed to arsenic in the workplace. In 1996, OSHAissued a memorandum stating that sputum cytology(part of the OSHA medical surveillance program) isnot appropriate in the surveillance of arsenic-exposedworkers and that worksites not performing sputumcytology would not be issued citations(Memorandum from OSHA Directorate ofCompliance Programs, August 1996).

Determination of urinary arsenic is not included inthe standard, although biologic monitoring forarsenic is available as a means of assessing exposureto arsenic compounds. Analysis for total arsenicmay be heavily influenced by organic arseniccompounds found in seafood.11 Biologic monitoringfor occupational exposure to arsenic is bestconducted by analyzing inorganic arsenic and itsmetabolites, monomethylarsonic acid and cacodylicacid, as these compounds represent only inorganicarsenic exposure.

Detection of arsenic in urine is an indication of arecent exposure only (within a few days); arsenic israpidly excreted in urine and has a biological half-life of only one or two days. Normal values of totalarsenic in urine vary from 13 to 46 :g/L.19 TheACGIH biological exposure index (BEI) foroccupational exposure to arsenic (includinginorganic arsenic and methylated metabolites) is50 micrograms per gram creatinine (ug/g creat) inurine samples taken at the end of a workweek.2

LeadLead is a bluish-gray heavy metal with nocharacteristic taste or smell and is ubiquitous in U.S.urban environments due to the widespread use oflead compounds in industry, gasoline, and paintsduring the past century. Absorbed lead accumulatesin the body in the soft tissues and bones. Lead isstored in bones for decades, and may cause healtheffects long after exposure as it is slowly released inthe body.

Lead can enter the body by inhalation or ingestionand can adversely affect numerous body systems.Skin absorption does not occur except for certainorgano-lead compounds such as tetraethyl lead.Although lead is a naturally occurring element, mostexposures to lead occur from human activities.20

Inhalation is considered to be the most importantoccupational exposure route. Lead is a systemicpoison that serves no useful function after absorptionin the body, the health consequences of which canoccur after periods of exposure as short as days or aslong as several years.21 Once absorbed, lead isexcreted from the body very slowly. Absorbed leadcan damage the kidneys, peripheral and centralnervous systems, and the blood forming organs(bone marrow).11 These effects may be felt asweakness, tiredness, irritability, digestivedisturbances, high blood pressure, kidney damage,mental deficiency, or slowed reaction times.Damage to the central nervous system in general,and the brain (encephalopathy) in particular, is oneof the most severe forms of lead poisoning.11,21

Chronic lead exposure is associated with infertilityand with fetal damage in pregnant women.11

Although the hazards of lead have been known forsome time, occupational exposure to lead is still asignificant problem in some industries (batteryreclamation, radiator repair, construction). In 1990,the U.S. Public Health Service established a nationalgoal to eliminate worker exposures resulting inblood lead (PbB) concentrations greater than25 micrograms per deciliter (:g/dl).22

Avondale is governed by the OSHA Maritime LeadStandard (CFR 1915.1025), which is identical to theGeneral Industry Lead Standard (CFR 1910.1025).The standard establishes a PEL for airborne lead of50 :g/m3, and an action level of 30 :g/m3.23,21 Theportion of the lead standard dealing with biologicmonitoring calls for employees exposed above theaction level to have available to them measurementof PbB and zinc protoporphyrin (ZPP) every sixmonths after initial testing is done. PbB levelsgreater than 40 micrograms (µg) per 100 grams(µg/100g [1 µg/100g = 1 µg/dl]) call for increasedtesting frequency, and PbB levels above 50 ug/100gcall for removal from exposure until the PbB level


falls below 40 µg/100g. The measurement of ZPP inthe blood is used in monitoring employees as ameasure of longer-term biologic effect of leadexposure.11,2 Measurements of ZPP of greater than 50µg/dl have been used as an indication of excess leadexposure.11,24 However, the ZPP test is felt to be aninsensitive and non-specific test for lower-leveloccupational exposure.2

A review of the correlation of airborne lead levelsand PbB levels suggests there is no good way tocorrelate airborne lead exposures with subsequentPbB levels.25

RESULTS

Industrial HygieneAccording to Avondale representatives, silica has notbeen used as an abrasive blasting agent since 1972,and there is currently no fiberglass work at theshipyard. All fiberglass work (including the use ofrelated chemicals acetone and styrene) wascompleted in May 1997, when the last of four NavyMinehunter vessels was refurbished.

Factory

Workplace Observations

All welding observed was on carbon steel;approximately 65% of the welding operations in theFactory, and 90% of the work in the UnitDepartment, were flux cored arc welding (FCAW).During FCAW, a consumable wire (0.052" diameterDualshield T-1 & T-2 Flux Core, ESAB Group,Inc.) is continuously fed through a welding gun. Thewire is hollow and filled with a flux core composedof various metals or minerals that promote the weldprocess by removing impurities and preventingoxidation. Shielding gas (carbon dioxide) issupplied at the gun tip to prevent oxidation of thebase metal during the FCAW process.

The remainder of the welders in the Factoryprimarily use the shielded metal arc welding

(SMAW or “stick welding”) process. For example,tacking of the tie-downs (or cloverleafs) onto grids inthe Unit Department was done with SMAW. TheSMAW technique requires the use of a hand held,flux-coated consumable electrode of a finite length toproduce an arc. No shield gas is used with thisprocess.

The ventilation system in the Factory consists ofridge vents which provide passive general ventilation(no mechanical general dilution ventilation has beeninstalled). Portable blowers are used in the UnitDepartment to provide large quantities of air duringsome confined space welding operations. Theportable ventilation units observed during this sitevisit consisted of collapsible duct with a blower,usually mounted on the top of the unit, that forces airinto the confined area where welding is occurring.

Welders wear half-mask air purifying respirators(APR) with either high efficiency air purifying(HEPA) filters or combination organic vaporcartridges with a particulate filter, when working inopen areas. According to Avondale representatives,welders are provided with supplied air respiratorswhen conducting certain tasks (Arc Gouging) inconfined areas, or when there is no forced airventilation for confined area work. No workerswearing supplied air respirators were observed.Welders also utilized welding hoods and protectivegloves. Some welding tasks require workers to stayin a fixed location for the majority of the work shift.Other welding tasks (e.g., tack welding tie-downs)required the workers to frequently move to differentlocations. No welding screens or shielding toprevent or reduce exposure to welding flash were inuse in the Factory

An automated welding process (“tripod welder”),which was installed as an ergonomic controlmeasure, was observed. The electrode waspositioned over the area to be welded, at an angle,situated in a tripod holder. This was a semi-automatic device; as the electrode melted, gravitypulled the electrode down and the weld traveledalong the work piece. After the electrode wasconsumed it was manually replaced with another


electrode and the tripod welder was moved furtherdown the piece.

Air Sampling Results

The results of the air samples collected from weldersin the Factory are shown in Table 1. The highestmeasured total particulate weld fume sample(55 mg/m3) was from a worker welding in a confinedarea (inside an Inner Bottom Unit) for approximately1.5 hours. Forced air ventilation was providedduring this work from a blower and collapsible ductsystem. This worker wore a half-mask APR with aHEPA filter while welding. The other four weldingfume samples were collected over the majority of thework shift (approximately 400 minutes), and the totalparticulate weld fume results ranged from3.15 mg/m3 to 19.1 mg/m3. Iron was the highestmeasured metal. The highest iron concentrationdetected (12.5 mg/m3) was in the sample from thewelder in the confined area. Exposures measured onthe other four welders ranged from 0.98 mg/m3 to6.1 mg/m3. The NIOSH REL for iron oxide fume is5 mg/m3. Measured lead concentrations ranged from0.003 mg/m3 to 0.010 mg/m3 and were all belowboth the NIOSH REL (0.1 mg/m3) and OSHA PEL(0.05 mg/m3). Arsenic was not detected in any of thesamples collected.

Shot House

All workers evaluated wore supplied-air abrasiveblasting respirators (Bullard 88 Type “CE”)equipped with a vortex tube for cooling. Theseworkers also wore half-mask APR’s equipped withHEPA filters as additional protection. Although theAPR’s were not an integral part of the blast hood, theworkers monitored indicated that use of theadditional respirator was a common practice duringabrasive blasting. Avondale representativesindicated the supplied air system is designed toprovide clean air at a delivery rate within a range of6 cubic feet per minute (cfm) to 15 cfm. Theseworkers also indicated the vortex tube providedconsiderable cooling during use and significantlyreduced heat exposure.

Abrasive blasting only occurs during the second(night shift) at Avondale. A review of thedecontamination trailer found the design to be sound.The trailer was equipped with a “dirty” and “clean”side, showers and lockers. Clean work clothes (twosets per day) are furnished by Avondale foremployees who work in the Shot House. Thedecontamination trailer has a dedicated lunchroomarea for workers; Avondale Safety and Healthrepresentatives indicated that periodic wipe samplingfor lead is conducted to verify the area is free fromcontamination.

Air Sampling Results

Eleven abrasive blasters were monitored in the ShotHouse on successive days (October 22-23, 1998).The results of the air sampling conducted in the ShotHouse are shown in Tables 2 (gravimetric) and3 (elemental). As previously described, three samplesets (inside the hood, outside the hood, “passive”)were collected from each abrasive blaster, and ontwo of the sample sets (outside the hood, passive),that portion of the sample that was loose bulk (largegrit) was separated and analyzed separately. All airsamples collected outside the abrasive blast hoodgreatly exceeded the OSHA PEL and ACGIH TLVfor total particulate and the NIOSH REL for iron forboth the “small particle”* (OH-A) and “largeparticle” (OH-B) fraction. The small particlegravimetric air sample results ranged from34.6 mg/m3 (AB #6) to 64.1 mg/m3 (AB #11). Thelarge particle component concentrations ranged from250.3 mg/m3 (AB #8) to 5860.7 mg/m3 (AB #9).Corresponding ranges of iron measured in the smallparticle portion of the sample were 15.2 mg/m3 (AB#6) to 29.2 mg/m3 (AB #5, #11), and 172.3 mg/m3

* For purposes of discussion, the “small particle” fractionof the sample is that portion remaining on the filter afterremoval of large loose grit from the filter cassette prior toanalysis. A more robust definition is not available as aspecific size range (e.g. minimum and maximum particlediameter) for the “small particle” fraction was notdetermined, but was subjectively determined by the analyst.The component of the sample removed (“large particle”)wasprimarily rebound shot and considered too large to pose aninhalation hazard.


Abrasive Blast Air Sam pling Results: Lead: Sm all Particle Fraction vs Large

Particle Fraction

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

1 2 3 4 5 6 7 8 9 10 11

Abrasive Blaster #

ug/m

3

Small Particle

Large Particle

Figure 1-Outside the Blast Hood Lead Results

Contribution of the Small Particle Fraction to the Total Particulate Concentration in Milligrams per Cubic Meter

Abrasive Blast Sampling: Outside the Blast Hood Samples

Small ParticleLarge Particle

Figure 2

(AB #8) to 1926 mg/m3 (AB #9). The NIOSH RELfor iron oxide dust (as iron) is 5 mg/m3.

The lead concentrations measured in the “outside thehood” samples ranged from 1 microgram per cubicmeter (µg/m3) to 10 µg/m3 for the small particlecomponent and 8 µg/m3 to 260 µg/m3 for the largeparticle portion (Figure 1). Four of the 11 arsenicsamples collected outside the hood exceeded theNIOSH REL of 2 µg/m3. These samples (largeparticle fraction) ranged from 30 µg/m3 to 50 µg/m3.

Several samples were between the analytical limit ofdetection (LOD) and the limit of quantification(LOQ), or had an LOD exceeding the NIOSH REL.The small particle component of one outside thehood arsenic sample (AB #11) showed a

concentration (8 µg/m3) that exceeded the NIOSHREL.

For the other elements measured in the “outside thehood” samples, manganese exceeded the NIOSHREL of 1.0 mg/m3 on the large particle component ofall samples, but not on any small particle fractions.For both copper (NIOSH REL = 1.0 mg/m3) andchromium (NIOSH REL = 0.5 mg/m3), the largeparticle portion of the sample exceeded the REL on3/11 samples, but on none of the small particleportions.

The outside the hood sample results show that thelarge particle steel grit component of the air sampleis the primary contributor to the reported totalconcentrations. That portion of the air sampleconsidered to represent the small particle fractionentailed an average of only 3.5 % of the totalgravimetric sampling results (Figure 2).The “passive” samples collected outside the workers

abrasive blast hood contained a highly variable butsignificant amount of inertia-driven (rebound) grit(Figure 3). The mass of grit detected on the“passive” samples ranged from 1.58 mg to 366.5 mg.If these weights were detected on a filter connectedto an air sampling pump with an average flow rate of2 l/m for 400 min (800 l volume), the range ofconcentrations would have been 2 mg/m3 to458 mg/m3. This finding further substantiates thecontention that there is a significant contribution of


Abras ive Blast Air Sam pling: M illigram s M easured: Active vs.

Pass ive Sam ples

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

2 5 0 0

1 2 3 4 5 6 7 8 9 10 11

Abras ive Blas ter #

Mill

igra

ms

Mea

sure

d

Passive M G OH-M G

Figure 3-Outside the Blast Hood (OH-MG) versus Passive Air Samples (Passive MG)

large particle aerosol when assessing exposure toabrasive blasting and collecting the sample outsidethe abrasive blast hood. All of the inside the hood air samples except arsenicwere below applicable NIOSH RELs. For some ofthe inside the hood air samples, the analytical LODfor arsenic exceeded the NIOSH REL, thusadherence to the REL could not be demonstrated.One sample (AB #6) showed an arsenicconcentration that was between the LOD and LOQ.Several of the metals measured were below theanalytical LOD. These results indicate the abrasiveblast hoods were being worn properly and wereproviding sufficient protection.

Respirator Efficacy

Because data was collected from both inside andoutside the supplied air respirator worn by theabrasive blasters, the efficacy of the respiratoryprotection was assessed for each worker. In general,the protection that a given respirator will provide isdetermined by multiplying the exposure limit for thecontaminant by the assigned protection factor (APF)for that specific class of respirators.26 The APF isconsidered the minimum anticipated level ofprotection a properly functioning respirator, or classof respirators, will provide to a percentage ofproperly trained and fitted users.26 The actualperformance of a correctly worn respirator underworkplace conditions is determined by calculatingthe workplace protection factor (WPF). The WPF isdefined as the ratio of the estimated contaminantconcentration outside the respirator to thecontaminant concentration inside the respirator(when TWA samples are collected simultaneouslywhile the respirator is properly worn during normalwork activities).26 During this survey, WPF’s werecalculated using the combined (small and largeparticle fraction) concentration for each contaminantmeasured to determine the effect of contaminantselection on the WPF (Figure 4). The lowestcalculated WPF using the combined measuredconcentrations showed a respirator protection factorof 2817. WPF’s for several of the workersmonitored were in excess of 10,000. WPFs werealso determined using that portion of the air sampleconsidered to represent the small particle fraction.Using the smaller size particle concentration, thecalculated WPFs were much lower, and ranged from183 to 1282 for the gravimetric measurements, and210 to 3700 for specific metal concentrations.Because some of the measured contaminants werenot detected in the inside the hood air samples, noWPFs’ were calculated for these components.


W orkplace Protection Factor by Contaminant Measured

0

2000

4000

6000

8000

1 0000

1 2000

1 2 3 4 5 6 7 8 9 1 0 1 1

Abrasive Blaster #

Wor

kpla

ce P

rote

ctio

n Fa

ctor

Gravim etricManganes eIronCopper

Figure 4 - Workplace Protection Factors Determinedby Contaminant Measured Using the Combined (smalland large particle) Concentration

Bulk Sampling Results

The results of the bulk samples are reported in Table4. The steel grit utilized for the blasting (MetgrainG-40, Chesapeake Specialty Products) has a sizerange of 0.0394 to 1.0 millimeter (mm) (all passthrough a #18 screen). The reject system is designedto discard all particles smaller than approximately212 µm (pass through a #65 mesh screen). Nocadmium was detected in any of the bulk samples;thus, no air samples were analyzed for this metal.The bulk samples showed elemental concentrationsof lead in the range of 4.3 µg/g (or part per million)in the virgin shot to 223.4 µg/g in the fine rejectsample, and arsenic in the range of 16.1 µg/g (finereject) to 74.1 µg/g (recycle grit). Analysis did notindicate that high iron concentrations interfere withdetecting low levels of lead or arsenic usinginductively coupled plasma emission spectroscopy(ICAP) as described in NIOSH Manual of Analytical

Methods, 4th edition, method #7300. There wassome variation in results between the twolaboratories as shown in the table.

Initial analysis of the bulk sample of steel plate(Steel Grade AH 36, U.S. Steel Group) from theFactory indicated a substantial lead contact (16,829ug/gm). However, analysis of a second sample andre-analysis of the first steel plate sample did notconfirm this initial finding and only low levels oflead were detected (10.8 ug/gm, 18 ug/gm,respectively). Analysis of the 2-part epoxy resin(Amercoat 3207 Cure and Resin) used as a pre-construction primer in the Factory found a low levelof lead (2.9 ug/gm) in the resin, and less thandetectable (<0.42 ug/gm) in the cure.

Medical

Records Review

Employees from welding-unit construction andshipfitting-unit construction in the Factory had71 entries in the OSHA 200 log for the first eightmonths of 1997. Welding-flash burns made up42 (59%) of the entries, with some of the otherentries consisting of chemical irritation (13 [18%]),heat stress (6 [8%]), musculoskeletal problems(3 [4%]), and chemical inhalation (3 [4%]).Employees from the paint department and paint-unitconstruction who conduct painting and/or abrasiveblasting in the Shot House had 33 entries in theOSHA 200 log, with 18 (55%) involving chemicalirritation, 6 (18%) involving abrasion, 5 (15%)involving contusion, and the remainder made up of1 each of “lung disease,” pleural plaques, rash, and“sand in face.”

Lead Program

At the time of the NIOSH site visit, there wereapproximately 70 Avondale employees participatingin the lead program. The number of participants inthe program was reported to vary depending on thetypes of work in the shipyard at any given time;employees potentially exposed to lead above the


action level, as identified by the industrial hygienedepartment, are enrolled in the lead surveillanceprogram. For example, during a recent refurbishingjob (American Heavy Lift) involving work with lead-containing material, 235 workers were entered intothe program. Some employees, such as employees inthe repair department and the Shot House, aremaintained in the lead program continuously.

Avondale lead air sampling results included347 measurements of airborne lead among73 different employees involved in abrasive blasting.The mean air lead concentration was 32.0 ug/m3

(median - 4.3 ug/m3; range - 0 to 1,071 ug/m3). Thebiologic monitoring data included 234 measurementsof PbB and ZPP among 67 different employeesinvolved in the abrasive blasting operation. Themean PbB level was 4.4 ug/dl (median - 4.0 ug/dl;range - 0 to 18 ug/dl). The mean ZPP level was 41.4ug/dl (median - 40.0 ug/dl; range - 22 to 72 ug/dl).Avondale reported that the PbB and ZPPdeterminations were performed by an OSHA-approved contract laboratory.

Arsenic

Avondale reported that all employees working in theShot House were enrolled in the arsenic exposuresurveillance program. The data from this programincluded measurements of total urine arsenic inemployees involved in the abrasive blastingoperation from January 1995 through October 1997.Ninety measurements were made among 54 differentemployees. The mean urine arsenic level for all testswas 41.3 micrograms per liter (ug/l) (median -30 ug/l; range - 0 to 180.3 ug/l). There were22 samples with a total arsenic level above theACGIH BEI (which excludes organic arsenic ofmarine origin) of 50 ug/g creatinine. Avondalereported at the time of the review that elevatedarsenic levels were followed-up with additionalmedical testing. As part of the arsenic surveillanceprogram, Avondale has been collecting sputumsamples as required by the original OSHA standard;none were found to be positive for malignancy.

DISCUSSIONWelding activities in the Factory result in substantialexposure to welding fume, and continued adherenceto the proper use of respiratory protection isnecessary until effective engineering oradministrative controls can be implemented. Withone exception, the use of respirators in the Factoryappeared to be adequately protecting workers. Onewelder working in a confined area (Inner Bottom) forapproximately 100 minutes had a measuredexposure of 55 mg/m3, despite the use of forced airventilation. This measured concentration andobservation of the work practices suggest a higherdegree (supplied air) of respiratory protection isneeded for this activity. A half-mask air purifyingrespirator has an assigned protection factor of 10,indicating that, if properly worn, the device wouldprovide protection in a contaminant concentration upto 10 times the applicable limit. As the ACGIH TLVfor welding fume is 5 mg/m3, the measuredconcentration (albeit not a full-shift TWAmeasurement) during confined area weldingexceeded this criterion by more than 10 times. Noother constituents of the weld plume (gases such ascarbon monoxide, fluorides, etc.) were measuredduring this survey, but it is likely that thesecontaminants are also generated during the weldingprocess.

The limited medical component of this HHE doesnot allow NIOSH investigators to draw conclusionsconcerning the potential occupational exposureswhich could account for the respiratory complaintsreported in the HHE request. Concentrations of aircontaminants (welding fume in the Factory, totalparticulate and metals in the Shot House) higher thanthose documented in our survey and/or improper useof respiratory protection among exposed workers arefactors that could potentially contribute to respiratoryhealth effects among these workers. Welding flashburns were the most commonly recorded injury inthe Factory, and there is a need to ensure thatappropriate shielding is used to reduce the potentialfor exposure, of both workers and others in the area,to the welding arc.


Because of the size of the Factory and the mobilityof the welders, ensuring an effective ventilationsystem to reduce welding fume exposures presents adifficult and complex design issue. Avondale hasbeen considering providing general dilutionventilation (GDV) or local exhaust ventilation(LEV). While GDV may result in some reduction inthe visible haze and overall contaminant levels, itwould likely have little impact in reducing exposuresfor welders. The benefit of LEV is efficiency bycontaminant capture at the point of generation. LEV,alone or in conjunction with GDV, would providesuperior protection to the welder as compared to justa general exhaust system for the facility.Implementation of effective LEV systems as acontrol option is complicated by the large number ofmobile welders in the Factory. Additionalinformation on ventilation as a welding fume controlis provided in Appendix B.

Although measured exposures outside the abrasiveblast hoods on all workers in the Shot Houseexceeded NIOSH RELs, all but one of the samplescollected inside the workers’ blast hoods indicatethat these devices are being used properly and aresufficiently protective. One sample for arsenicshowed an inside-the-hood concentration that wasbetween the analytical LOD and LOQ. Additionalprotection is afforded by the work practice ofwearing a half-mask APR with HEPA filter toaugment the blast hood. All PbB levels were< 20 ug/dl. The company’s biological monitoringand air sampling data, as well as the NIOSH airsampling data, indicate that the Shot House safetyand health program is effective in protecting againstoverexposure to lead.

The source of the lead detected in the Shot Housedoes not appear to be materials from the Factory.The airborne lead is likely due to the small amountspresent in the steel grit. From the limited number ofsamples collected, it appears that the lead content ofthe small fine component of the abrasive grit ishigher than in the new, or larger-size, grit. Onepossible explanation for this finding is that duringuse, finer lead dust particles are continuouslygenerated from the fracturing of grit during blasting,

and then recirculated through the system, resulting ina build-up of lead in the recycle stream.

PBZ arsenic concentrations outside the blast hoodexceeded the NIOSH REL of 2 µg/m3, indicatingthat the potential for arsenic exposure does existduring blasting operations in the Shot House. Aswith lead, the arsenic appears to come from the steelgrit, and the levels vary with the type of grit. Thetotal urinary arsenic concentrations, determined aspart of the medical surveillance program for arsenic,cannot be effectively used to monitor occupationalexposure unless seafood has not been consumed for2-3 days prior to the testing. Preferably, the urineshould be analyzed specifically for inorganic arsenicand its metabolites.27

Current sampling and analytical methodology forevaluating exposure during abrasive blasting entailcollecting a particulate air sample outside theabrasive blast hood. Air samples collected duringthis HHE support the contention that these methodsdo not accurately represent worker exposure toinhalable lead and other elements during abrasiveblasting in confined spaces. This is because largeabrasive blasting grit particles enter the samplingcassette inlet from inertia (high velocity rebound)rather than through the action of the sampling pump,where an airborne contaminant is collected in an airsample of known volume. In the absence ofguidelines for the analysis of samples containinglarge, non-inhalable particles, all dust and grit on thesample filter is digested, analyzed, and the totalamount of the selected airborne contaminant (e.g.,lead), is reported. Including these large, non-inhalable particles in the analysis may thusoverestimate the concentration of inhalable lead (orother metals).

This evaluation is consistent with a previous NIOSHevaluation of a shipyard abrasive blasting operationthat found abrasive blaster exposures to lead inexcess of OSHA PELs despite the presence of onlylow levels in the base metal, surface coatings, andsteel grit.28 Bulk samples collected during that studyfound that the grit contributed the greatest amount oflead and other metals. Standard sampling methods


used to assess exposure resulted in large, non-inhalable particles entering the monitoring cassettedue to high initial velocity. Even the relatively smallamount of lead in grit (approximately100 micrograms per gram grit) resulted in asignificant contribution to the lead in the samples;primarily from the random entrapment of large gritparticles in the filter cassettes. Other samplingmethods assessed in that study included placing thesampling cassette behind the worker, use of a metalshield to guard the cassette inlet, and the use of astandard nylon cyclone. Sample placement and theuse of the shield did not reliably prevent large gritparticles from entering the cassette, and cycloneswere not useful because they frequently becameinverted as the blaster worked in confined areas.28

Even if they did perform effectively in thisenvironment, cyclones would not be an appropriatemeasurement choice because they exclude all but therespirable fraction. The investigators concluded thatconventional sampling and analytical techniquesresult in an overestimation of worker exposures tolead and other contaminants present in abrasiveblasting environments.

This issue is of considerable importance from aregulatory standpoint, as administrative andengineering controls prescribed by the OSHA leadstandard are triggered by full-shift personal leadexposures in excess of the action level outside theblasting hood.

Determination of respirator efficiency by calculatingthe WPF indicated that the abrasive blast hoods wereperforming well. There was considerable variabilityin the WPF depending on which contaminant wasselected for the calculation or when the small particlefraction alone was used in the calculation. For someof the measured contaminants, analytical variabilityassociated with the low concentrations detected mayhave influenced these results. A previous study thatevaluated the performance of abrasive blast hoodsduring the use of silica in a sand blasting booth foundan average WPF of 16,800 (geometric mean).29

CONCLUSIONSMonitored exposures to welding fume componentsexceeded applicable guidelines in the Factory.However, except for one of the workers, therespiratory protection worn by Factory welders wassufficiently protective. Despite the use of forced airventilation during welding in confined areas, onePBZ sample exceeded 50 mg/m3, thus warranting ahigher level of respiratory protection than iscurrently used for that activity until engineering orwork practice controls are implemented.Observations of work practices in the Factorysuggest that the most likely choices for local exhaustventilation systems are movable hoods and fumeextraction guns.

Measured exposures to iron, manganese, and othermetals collected outside the workers abrasive blasthood in the Shot House exceeded NIOSH RELs; allmeasured exposures collected inside the abrasiveblast hood were below NIOSH RELs, or had areported limit of detection that was greater than theREL. The source of lead and arsenic contaminationin the Shot House is likely the steel grit used as theabrasive blasting agent. Significant levels of lead orarsenic were not detected in the Factory. The safetyand health program in the Shot House, and thecontrols in place ( PPE, administrative, engineering)during abrasive blasting appear to be effectivelypreventing worker exposure to lead and othercontaminants during abrasive blasting operations.However, the biologic monitoring program forarsenic currently uses measurement of urinary totalarsenic; these values cannot be interpreted withouttaking into account dietary organic sources ofarsenic. Evaluation of the abrasive blast hoodperformance found that there is a wide variability inthe calculated workplace protection factor dependingon the contaminant selected.

Current sampling and analytical methods do notaccurately represent employee exposure to lead orother contaminants during abrasive blasting.Measurement methods that more accurately estimatethe true exposure during abrasive blasting operations


are needed. There are no methods currentlyavailable to reliably collect a representative sampleoutside the abrasive blast hood. As such, it appearsthat collecting a sample inside the abrasive blasthood is more representative of the workers’ exposureand avoids the significant confounding factor oflarge, non-inhalable materials. Air sampling resultsobtained outside the abrasive blast hood may triggerOSHA regulatory requirements for engineeringcontrols, respiratory protection, medical monitoring,etc. Samples collected inside a properly selected andused abrasive blasting hood should result in levelsbelow regulatory action limits. This however,should not relieve the employer of responsibility toimplement engineering and work practice controls asthe primary control method.

RECOMMENDATIONS

Welding in the FactoryThe following recommendations are applicable onlyfor those areas evaluated; the ventilationconfiguration in one work area may not be applicableto another work area due to differences in thewelding operations and process layout.

(1) Investigate and implement, where feasible, fumeextraction guns for flux-cored arc welding processes,particularly during welding operations which areenclosed or semi-enclosed. Fume extraction gunscan only be used with continuous wire feed weldingoperations such as FCAW, and are not available forstick welding operations. For fume extraction gunsto be used successfully, the following concerns needto be addressed:

(A) Educate welders on the proper use of thefume extraction gun. For it to be usedefficiently, welders may need to adjust theirtechnique slightly to account for the added sizeand weight of the gun.

(B) Ensure the ventilation is effectivelyexhausting the welding fume without disturbingthe shielding gas. This requires a balancing of

the shielding gas flow rate and the ventilationexhaust rate. Welders should be involved and/oreducated in the proper selection of exhaust ratesso that they do not modify the ventilation laterand potentially decrease the effectiveness of theguns.

(C) Exhaust contaminated air to the outside andpractice preventive maintenance of theventilation system. This includes periodicinspection of the welding gun nozzle to ensurethe exhaust orifices are not clogged.

(2) Implement local exhaust ventilation in theFactory for confined space welding operations.While the blowers currently used may help to dilutethe welding fume concentration, the addition of anexhaust system would help to reduce the amount offume in the immediate vicinity of the work area.Mechanical exhaust ventilation might be provided byrouting 4"-8" flexible tubing into the work space andconnecting it to a portable local exhaust ventilationunit. This type of setup would be adaptable to anumber of process configurations. The duct work(tubing) for the ventilation system should not blockthe welder’s means of access to and from theconfined work space. Duct adapters are available foruse with confined spaces.30

(3) Consider implementation of local exhaustventilation for welding operations throughout theFactory. Due to the nature of the work in theshipyard, it may not be possible to automate orisolate certain welding processes. Stringentshipbuilding specifications may also limit the use ofprocess substitutions. As such, the control of choiceat the shipyard may be ventilation. Considerationsbefore implementing controls include:

(A) Ensure the local exhaust ventilation systemdoes not obstruct movement and activities of theoverhead bridge crane, particularly in the UnitDepartment. Possibilities include installing theLEV system on a traversing rail along theequipment lane or mounting the LEV system onthe structural posts in the equipment lane. Onemanufacturer’s literature shows an articulating


1. NIOSH [1992]. Recommendations foroccupational safety and health: compendium ofpolicy documents and statements. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control, National Institute for

arm unit which can be mounted on a carriage thattravels along an extraction rail (front reach ofabout 14', 360 degree rotation).31

(B) Local exhaust ventilation systems should beaccessible from a variety of welding positions.For example in the Unit Department, if the LEVsystem is mounted on posts in the equipmentlanes, welding performed close to the middle ofthe department, near the walkway, may not beadequately controlled unless the articulatingarms can reach welding operations 60 feet away.Since a reach that great may not be probable,LEV systems would need to be positioned atlocations other than just the equipment lanes.

(4) Use welding curtains, screens, or tarps aroundwelding operations to help prevent welder’s flashhazards, particularly in the Fabrication and WebDepartments. According to OSHA 29 CFR 1915.56,whenever practicable, arc welding and cuttingoperations shall be shielded by screens to protectnearby personnel from the arc flash. If it isimpractical to place curtains or screens around thewelding operations, determine if they can at least bepositioned between work areas and the walkways toprotect nearby personnel from welder’s flash.Workers adjacent to welding operations should uselong gloves and personal hoods to protectthemselves against unshielded welding flashes.

(5) Continue participating in the NAVSEAEmissions Working Group to learn of new controlideas or successful ventilation efforts implemented inother shipyards which may be applicable toAvondale.

(6) Evaluate specific welding tasks and implementautomation options where feasible. An example ofpartial automation already observed in the shipyardwas that of the tripod welder which allowed thewelder to maintain some distance between himselfand the welding process.

(7) Until a ventilation or other controls have beenimplemented and comprehensively evaluated toensure effectiveness, respiratory protection should

continue to be used when welding in the Factory.Supplied air respirators offering a higher degree ofprotection should be used when working in confinedarea such as the Inner Bottom Units, even if a forcedair blower is utilized.

Safety and Health ProgramAvondale should ensure that Industrial Hygiene andSafety review is obtained and incorporated duringthe early conceptual or design phase for new orremodeled facilities and processes. Anticipatingpotential health and safety issues and providing forappropriate controls and safeguards during the initialplanning stages of projects is an effective means ofpreventing future problems and avoiding costly re-design and retrofits.

Employees should be encouraged to report allpotential work-related health symptoms toappropriate health care personnel. Avondale shouldmonitor reported health complaints in a systemdesigned to identify particular job duties, workmaterials, or areas which may be associated withparticular health effects.

Biologic monitoring for arsenic should allow forspecific determination of exposure to inorganicarsenic, preferably by speciation of the arsenic in aurine sample. Inorganic arsenic and its metabolitescan be distinguished from the non-toxic organicarsenic found in seafood.

Continued collection of sputum samples as part of amedical surveillance program for occupationalarsenic exposure is not of preventive medical valueand is no longer required by OSHA.

REFERENCES


Occupational Safety and Health, DHHS (NIOSH)Publication No. 92-100.

2. ACGIH [1996]. 1996 TLVs® and BEIs®:threshold limit values for chemical substances andphysical agents and biological exposure indices.Cincinnati, OH: American Conference ofGovernmental Industrial Hygienists.

3. Code of Federal Regulations [1989]. 29 CFR1910.1000. Washington, DC: U.S. GovernmentPrinting Office, Federal Register.

4. Stern RM [1979]. Control technology forimprovement of welding hygiene, somepreliminary considerations. Copenhagen,Denmark: The Danish Welding Institute, TheWorking Environment Research Group, ISBN 87-87806-18-5, p. 2.

5. Burgess, WA: Recognition of HealthHazards in Industry. A Review of Materials andProcesses. Industrial Operations, Welding. Ed:John Wiley & Sons, New York.

6. The Welding Institute [1976]. The factsabout fume - a welding engineer’s handbook.Abington, Cambridge, England: The WeldingInstitute.

7. NIOSH [1988]. Criteria for a recommendedstandard: occupational exposure to welding,brazing, and thermal cutting. Cincinnati, OH:U.S. Department of Health and Human Services,Public Health Service, Centers for DiseaseControl, National Institute for OccupationalSafety and Health, DHHS (NIOSH) PublicationNo. 88-110.

8. Rekus JF [1990]. Health hazards in welding.Body Shop Business 11:66-77, 188.

9. CFR. Code of Federal Regulations [1994].Occupational Safety and Health Administration: OSHA Table Z-2. 29 CFR 1910.1000.Washington, DC: U.S. Government PrintingOffice, Federal Register.

10. NIOSH [1994]. NIOSH pocket guide tochemical hazards. Cincinnati, OH: U.S.Department of Health and Human Services, PublicHealth Service, Centers for Disease Control andPrevention, National Institute for OccupationalSafety and Health, DHHS (NIOSH) PublicationNo. 94-116.

11. Hathaway GJ, Proctor NH, Hughes JP[1996]. Chemical hazards of the workplace, 4th.Ed. New York: Van Nostrand ReinholdCompany.

12. Clayton GD, Clayton FE [1978]. Patty'sIndustrial Hygiene and Toxicology. Vol I --General Principles, 3rd Revised Ed. New York:John Wiley & Sons.

13. NIOSH [1992]. Alert: request for assistancein preventing silicosis and deaths fromsandblasting. Cincinnati, OH: U.S. Department ofHealth and Human Services, Public HealthService, Centers for Disease Control, NationalInstitute for Occupational Safety and Health,DHHS (NIOSH) Publication No. 92-102.

14. NIOSH [1987]. Guide to industrialrespiratory protection. Cincinnati, OH: U.S.Department of Health and Human Services, PublicHealth Service, Centers for Disease Control,National Institute for Occupational Safety andHealth, DHHS (NIOSH) Publication No. 87-116

15. Hubbard, G [1996]. Metal exposure during afactory-based abrasive blasting operation. Appl.Occup. Environ. Hyg. 11(9):1108-1110.

16. Lauwerys RR and Hoet P. [1993]. Industrialchemical exposure - guidelines for biologicalmonitoring. 2nd Edition. Lewis Publishers, BocaRaton, FL.

17. ATSDR [1993]. Toxicological profile forarsenic. U.S. Department of Health and HumanServices, Public Health Service, Agency for ToxicSubstances and Disease Registry.


18. NTP [1998]. Eighth annual report oncarcinogens. Research Triangle Park, NC: U.S.Department of Health and Human Services, PublicHealth Service, National Institute ofEnvironmental Health Sciences, NationalToxicology Program.

19. HSDB [1991]. Hazardous substance databank, U.S. National Library of Medicine. SilverPlatter (CHEM-BANK, May 1991), Boston, USA.

20. ATSDR [1993]. Toxicological profile forlead: update. U.S. Department of Health andHuman Services, Public Health Service, Agencyfor Toxic Substances and Disease Registry.Publication: ATSDR/TP-12.

21. 29 CFR 1910.1025. Code of Federalregulations. Washington, DC: U.S. GovernmentPrinting Office, Office of the Federal Register.

22. PHS [1990]. Health people 2000: nationalhealth promotion and disease preventionobjectives. U.S. Department of Health andHuman Services, Public Health Service. DHSS(PHS) Publication No. 91-50212.

23. 29 CFR 1926.62. Code of FederalRegulations. Washington, DC: U.S. GovernmentPrinting Office, Office of the Federal Register.

24. Rom W, ed. [1992]. Environmental andoccupational medicine. Little, Brown, andCompany: Boston.

25. WHO. World Health Organization. [1980].Report of a study group: recommended health-based limits in occupational exposure to heavymetals. Technical report series 647. Geneva.

26. NIOSH [1987]. NIOSH respirator decisionlogic. Cincinnati, OH: U.S. Department of Healthand Human Services, Public Health Service,Centers for Disease Control, National Institute forOccupational Safety and Health, DHHS (NIOSH)Publication No. 87-108.

27. Franzblau A [1994]. Arsenic. In:Rosenstock L, Cullen MR (eds.) Textbook ofClinical Occupational and EnvironmentalMedicine. WB Saunders Co., Philadelphia, PApp. 732-734.

28. NIOSH [1996]. Health hazard evaluationreport: Bath Iron Works Corporation, Bath,Maine. Cincinnati, OH: U.S. Department ofHealth and Human Services, Public HealthService, Centers for Disease Control andPrevention, National Institute for OccupationalSafety and Health, NIOSH Report No. HETA 94-0122-2578.

29. Hammond, Y [1997]. Evaluation of theperformance of abrasive blasting respirators.Ann. Occup. Hyg. 41(Supplement 1):673-676.

30. Coppus [1992]. Man way Duct Adapter.Product Literature, 9-92Am. Worcester, MA.

31. Plymovent [1995]. Clean Fresh Air. ProductLiterature. Edison, NJ.


Table 1Personal Sampling Results - Welding: Gravimetric and ElementalAvondale Shipyard Factory Building, Day Shift: HETA 97-0260

October 22, 1997

Task Monitored Sample #s

MinutesSampled

Contaminants Detected TWA Concentration mg/m3

REL mg/m3

Track Welding onPlaten 40 at Pole

D-78, Arc Gougingfor 1.5 hours

339233621997

394

Total Weight (Gravimetric) 14.1 LFC

Lead 0.004 0.1

Arsenic <0.003 0.002

Manganese 0.64 1.0

Iron 6.1 5.0

Copper 0.07 0.1

Chromium 0.01 0.5

Flux Core weldingon mild steel. Inner

Bottom Unit 26,C3

33783406 416


Lead 0.003 0.1

Arsenic <0.003 0.002

Manganese 1.53 1.0

Iron 2.61 5.0

Copper 0.007 0.1

Chromium 0.005 0.5

Stick and FluxCore welding on

mild steel. Platen 20, B3

33663395 427


Lead 0.003 0.1

Arsenic <0.002 0.002

Manganese 0.24 1.0

Iron 0.98 5.0

Copper 0.009 0.1

Chromium 0.002 0.5

Flux Core weldingon mild steel ontop of Platen 20,

B3, Unit 108

34043402 422


Lead 0.004 0.1

Arsenic <0.002 0.002

Manganese 2.1 1.0

Iron 4.2 5.0

Copper 0.01 0.1

Chromium 0.007 0.5

Table 1Personal Sampling Results - Welding: Gravimetric and ElementalAvondale Shipyard Factory Building, Day Shift: HETA 97-0260

October 22, 1997

Task Monitored Sample #s

MinutesSampled

Contaminants Detected TWA Concentration mg/m3

REL mg/m3


Flux Core Weldingin Inner Bottom -confined area.

Samplingconducted for

duration of activity

3398 99 Total Weight (Gravimetric) 55.5 LFC

Lead 0.01 0.1

Arsenic <0.005 0.002

Manganese 7.33 1.0

Iron 12.5 5.0

Copper 0.01 0.1

Chromium 0.02 0.5NOTES:Gravimetric = Total weight of contaminants detected on filtermg/m3 = milligrams of contaminant per cubic meter of airTWA = time-weighted average concentrationAll samples were field blank correctedREL = NIOSH Recommended Exposure Limit for a 10-Hour TWALFC = Lowest Feasible ConcentrationAll Welders wore ½ mask air-purifying respirators with Dust-Mist-Fume filters or organic vapor cartridges withpre-filters.


Table 2Abrasive Blast House (Unit 265 and 106) Gravimetric Sampling Results

Inside and Outside Blast Hood, Passive: October 22-23, 1997 Avondale Shipyards: HETA 97-0260

Sample #, AB #

Time (min)

OH(A) mg/m3

TWA OH(A)

OH(B) mg/m3

TWA OH(B)

TWAOH(C)

Total mg

P(A)mg

P(B)mg

P(C)mg

OH(C)minus P(C)

IH mg/m3

WPF

OH-A/IH OH-C/IH

3382AB #1

16:24-18:04(100)

65.3

44.0mg/m3

1253.1

538.6mg/m3

582.6mg/m3

271.6 0.51 1.07 1.58 579mg/m3

0.24 183 2427.53163AB #1

18:04-19:54(110)

29.5 27.4

3182AB #1

20:48-21:35(49)

33.2 227.8

3411AB #2

16:27-18:26(120)

40.7

45.2mg/m3

678.9

602.3mg/m3

647.5mg/m3

292.7 1.74 101.5 103.3 419.3mg/m3

0.23 196 28173174AB #2

18:27-19:58(90)

57 240.9

3137AB #2

21:03-21:44(41)

32.5 1173.6

3388AB #3

16:32-18:24(112)

44.4

41.0mg/m3

2538.1

1352.0mg/m3

1393mg/m3

571.2 ND 19.5 19.5 1345.6mg/m3

0.20 205 69653153AB #3

18:40-19:56(76)

41.4 685.1

3168AB #3

20:28-21:30(62)

34.5 26.9

3386AB #4

16:52-18:28(96)

39.3

42.4mg/m3

2626.6

1572.9mg/m3

1615.3mg/m3

851.2 5.1 25.35 30.45 1573.2mg/m3

0.12 353 >10,0003165AB #4

18:28-20:04(96)

56.3 1649.7

3130AB #4

20:49-22:00(71)

27.6 44.5



Sample #, AB #

Time (min)

OH(A) mg/m3

TWA OH(A)

OH(B) mg/m3

TWA OH(B)

TWAOH(C)

Total mg

P(A)mg

P(B)mg

P(C)mg

OH(C)minus P(C)

IH mg/m3

WPF

OH-A/IH OH-C/IH


3222AB #5

16:45-18:10(85)

97.8

61.9mg/m3

1181.6

516.8mg/m3

578.7mg/m3

273.5 0.31 2.96 3.27 571.7mg/m3

0.07 884 82673179AB #5

18:10-20:00(110)

29.1 45.3

3173AB #5

20:52-21:31(39)

76.0 397.5

3394AB #6

16:41-18:24(103)

44.0

34.6mg/m3

1234.8

1017.1mg/m3

1051.7mg/m3

457.7 0.38 17.72 18.1 1010.1mg/m3

0.06 577 >10,0003136AB #6

18:24-20:00(96)

29.0 1340.3

3152AB #6

20:22-21:19(57)

27.0 79.3

3127AB #7

16:43-18:34(111)

63.0

58.8mg/m3

323.6

719.5mg/m3

778.3mg/m3

273.2 1.78 364.7 366.5 NC 0.12 490 64863230

AB #720:16-21:40

(84)53.31 1242.6

3363AB #8

17:01-18:27(88)

67.7

41.9mg/m3

287.8

250.3mg/m3

292.2mg/m3

125.9 2.12 ND 2.12 286.3mg/m3

0.06 698 48703129AB #8

18:27-20:00(93)

28.4 301.2

3133**AB #8

20:31-21:14(43)

18.1 63.3

3134AB #9

16:57-18:27(90)

74.5

47.6mg/m3

10,910

5860.7mg/m3

5908.3mg/m3

2245.2 0.79 80.95 81.7 5691.9mg/m3

<0.05 ND >10,0003181AB #9

18:27-19:52(85)

38.4 4,555



Sample #, AB #

Time (min)

OH(A) mg/m3

TWA OH(A)

OH(B) mg/m3

TWA OH(B)

TWAOH(C)

Total mg

P(A)mg

P(B)mg

P(C)mg

OH(C)minus P(C)

IH mg/m3

WPF

OH-A/IH OH-C/IH

Page 24 Health Hazard Evaluation Report No. 97-0260-2716

3380AB #9

20:28-21:29 (61) 20.7 230.3

3370AB #10

26:53-18:26(92)

48.0

57.1mg/m3

2150

1753.5mg/m3

1810.6mg/m3

857.5 1.92 219 221 1344mg/m3

0.05 1142 >10,0003377AB #10

18:26-19:59(93)

57.7 1192.4

3391AB #10

20:25-21:28(63)

69.6 2002.8

3161AB #11

16:51-18:20(99)

48.6

64.1mg/m3

1363.4

635.4mg/m3

699.5mg/m3

351.1 0.75 40.31 41.1 617.5mg/m3

0.05 1282 >10,0003407AB #11

18:20-19:54(94)

113.6 260.5

3175AB #11

20:19-21:11(58)

10.2 <.17

NOTES:A = Smaller size fraction remaining on filter after removal of the loose bulk. OH = Outside Blast Hood SampleB = Larger size particulate fraction (loose bulk) removed from filter and analyzed separately P = “passive” sample, closed face filter, obtained outside Blast HoodC = Total (A + B) IH = Inside Blast Hood Samplemg/m3 = milligrams of contaminant per cubic meter of sampled air. AB # = Abrasive Worker Individual Identifier NumberTWA = time-weighted average concentration ND = No particulate present and sample was not analyzed.

WPF = workplace protection factor: defined as the ratio of the measured contaminant concentration outside the respirator face piece to the contaminant concentration inside the respirator face piece (OH-C/IH). The samples were takensimultaneously while the respirator was being properly worn and used during normal work activities. Two sets of WPFs were calculated: OH-A/IH (using the smaller particle fraction concentration; OH-C/IH, using the totalmeasured concentration)

The passive samples were worn by the worker for the duration of the workshift. The filter cassette was fixed to the workers lapel and the filter side cap removed. No air was drawn through the filter.NC = The sample set was not compared because one OH sample was lost due to pump damage

** = This sample was collected when the worker was conducting compressed air blowdown and cleanup activities.AB# 1-5 were sampled on October 22, AB# 6-11 were sampled on October 23


Table 3Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive Avondale Shipyards: HETA 97-0260

October 22-23, 1997

Element OH(A), (mg/m3) OH(B), (mg/m3) OH(C), (mg/m3) P(A), (µg) P(B), (µg) P(C), (µg) OH(C) minus P(C) IH (µg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

AB #1

Lead 0.007 0.03 0.037 <0.2 <0.5 <0.5 0.037 mg/m3 <0.5 ND 0.1 mg/m3

Arsenic <0.005 <0.1 <0.1 <0.9 <3.0 <3.0 <0.1 mg/m3 <2.0 ND 2 µg/m3 (C)

Manganese 0.21 1.49 1.7 1.4 1.6 3.0 1.7 mg/m3 1.0 210 1700 1.0 mg/m3

Iron 18.4 448.3 466.7 99 1000 1099 464.4 mg/m3 84.7 217 5510 5.0 mg/m3

Copper 0.04 0.89 0.93 0.23 0.31 0.54 0.92 mg/m3 0.17 235 5470 1.0 mg/m3

Chromium 0.016 0.29 0.31 <0.2 <0.5 <0.5 0.31 mg/m3 (0.7) ND 0.5 mg/m3

AB #2

Lead 0.007 0.04 0.047 (0.2) 5.2 5.2 0.035 mg/m3 <0.7 ND 0.1 mg/m3

Arsenic (0.005) (0.02) (0.02) <0.9 <3 <3 (0.02) mg/m3 <3.0 ND 2 µg/m3 (C)

Manganese 0.24 2.3 2.54 14 150 164 2.18 mg/m3 0.9 266 2822 1.0 mg/m3

Iron 18.6 431.6 450.2 2000 100,000 102,000 224.4 mg/m3 69.1 269 6515 5.0 mg/m3

Copper 0.05 0.54 0.59 2.3 70 72.3 0.43 mg/m3 0.16 312 3688 1.0 mg/m3

Chromium 0.01 0.23 0.24 1.2 30 31.2 O.17 mg/m3 (0.7) ND 0.5 mg/m3

AB #3

Lead 0.009 0.06 0.069 <0.08 <0.2 <0.2 0.069 mg/m3 <0.5 ND 0.1 mg/m3

Arsenic (0.007) <0.1 (0.007) <0.9 <3 <3 (0.007) mg/m3 <2.2 ND 2 µg/m3 (C)

Manganese 0.20 3.16 3.36 6.0 30 36 3.27 mg/m3 0.6 333 5600 1.0 mg/m3



October 22-23, 1997


OH(A)/IH OH(C)/IH


Iron 16.4 1107.1 1123.5 750 14000 14750 1087.5 mg/m3 54 304 <10,000 5.0 mg/m3

Copper 0.05 1.2 1.25 1.2 9.8 11.0 1.22 mg/m3 0.20 250 6250 1.0 mg/m3

Chromium 0.02 0.06 0.62 (0.3) 4.2 4.2 0.61 mg/m3 (0.7) ND 0.5 mg/m3

AB #4

Lead 0.01 0.29 0.30 (0.5) (0.1) (0.5) 0.3 mg/m3 <0.4 ND 0.1 mg/m3

Arsenic <0.005 0.03 0.03 <0.9 <3.0 <3.0 0.03 mg/m3 <1.9 ND 2 µg/m3 (C)

Manganese 0.21 8.6 8.81 31 43 74 8.67 mg/m3 0.5 420 >10,000 1.0 mg/m3

Iron 15.5 689.2 704.7 2500 24,000 26,500 653.9 mg/m3 39.5 392 >10,000 5.0 mg/m3

Copper 0.05 1.7 1.75 3.7 15 18.7 1.71 mg/m3 0.12 416 >10,000 1.0 mg/m3

Chromium 0.02 0.6 0.62 2.2 3.6 5.8 0.61 mg/m3 (0.6) ND 0.5 mg/m3

AB #5

Lead 0.01 0.04 0.05 (0.06) <0.08 (0.06) 0.05 mg/m3 <0.7 ND 0.1 mg/m3

Arsenic (0.007) (0.01) (0.01) <0.9 <3 <3 (0.01) mg/m3 <0.21 ND 2 µg/m3 (C)

Manganese 0.33 2.18 2.51 1.2 0.83 2.03 2.51 mg/m3 0.2 1650 >10,000 1.0 mg/m3

Iron 29.2 312.2 341.4 69 3000 3069 333.6 mg/m3 20.4 1431 >10,000 5.0 mg/m3

Copper 0.09 0.63 0.72 0.19 0.84 1.03 0.72 mg/m3 (0.02) ND 1.0 mg/m3

Chromium 0.02 0.24 0.26 <0.2 <0.5 <0.5 0.26 mg/m3 (0.5) ND



October 22-23, 1997


OH(A)/IH OH(C)/IH


AB #6

Lead 0.006 0.02 0.026 <0.2 <0.8 <0.8 0.026 mg/m3 <1.0 ND 0.1 mg/m3

Arsenic (0.005) (0.09) (0.09) <0.9 <3 <3 (0.09) mg/m3 (3.8) ND 2 µg/m3 (C)

Manganese 0.19 2.7 2.89 3.0 38 41 2.80 mg/m3 0.5 380 5780 1.0 mg/m3

Iron 15.2 865.1 880.3 1500 17,000 18,500 837.8 mg/m3 33.3 456 >10,000 5.0 mg/m3

Copper 0.03 0.82 0.85 1.4 15 16.4 0.81 mg/m3 (0.04) ND 1.0 mg/m3

Chromium 0.02 0.47 0.49 <0.2 14 14 0.46 mg/m3 <0.4 ND 0.5 mg/m3

AB #7

Lead 0.006 0.02 0.026 (0.2) 3.5 3.5 NC <0.8 ND 0.1 mg/m3

Arsenic (0.005) 0.03 0.03 <0.9 (20) (20) NC <1.9 ND 2 µg/m3 (C)

Manganese 0.4 3.4 3.8 100 720 820 NC 0.8 500 4750 1.0 mg/m3

Iron 28.7 486.7 515.4 17,000 360,000 377,000 NC 50.5 568 >10,000 5.0 mg/m3

Copper 0.07 0.6 0.67 12 310 322 NC (0.04) ND 1.0 mg/m3

Chromium 0.02 0.3 0.32 4.8 160 164.8 NC <0.4 ND 0.5 mg/m3

AB #8

Lead 0.002 0.008 0.01 0.12 NA 0.12 0.009 mg/m3 <0.6 ND 0.1 mg/m3

Arsenic (0.002) <0.02 (0.002) <0.9 NA <0.9 ND mg/m3 <2.6 ND 2 µg/m3 (C)

Manganese 0.22 1.01 1.23 5.7 NA 5.7 1.22 mg/m3 0.6 367 2050 1.0 mg/m3



October 22-23, 1997


OH(A)/IH OH(C)/IH


Iron 18 172.3 190.3 420 NA 420 189.3 mg/m3 41.1 438 4630 5.0 mg/m3

Copper 0.06 0.23 0.29 0.91 NA 0.91 0.29 mg/m3 (0.03) ND 1.0 mg/m3

Chromium 0.02 0.11 0.13 (0.2) NA (0.2) 0.13 mg/m3 <0.6 ND 0.5 mg/m3

AB #9

Lead 0.001 0.07 0.071 (0.3) 0.81 0.81 0.07 mg/m3 <0.5 ND 0.1 mg/m3

Arsenic (0.007) <0.03 (0.007) <0.9 (3) (3) ND mg/m3 <2.4 ND 2 µg/m3 (C)

Manganese 0.28 6.4 6.68 6.0 280 286 5.9 mg/m3 <0.1 ND 1.0 mg/m3

Iron 18.5 1926 1944.5 1100 82,000 83,100 1725.8 mg/m3 5 3700 >10,000 5.0 mg/m3

Copper 0.04 2.4 2.44 1.6 75 76.6 2.24 mg/m3 <0.08 ND 1.0 mg/m3

Chromium 0.02 1.23 1.25 (0.4) 50 50 1.12 mg/m3 <0.05 ND 0.5 mg/m3

AB #10

Lead (0.001) 0.08 0.08 <0.2 (100) (100) 0.08 mg/m3 <0.5 ND 0.1 mg/m3

Arsenic (0.005) 0.05 0.05 <0.9 <3 <3 0.05 mg/m3 <0.21 ND 2 µg/m3 (C)

Manganese 0.36 8.27 8.63 18 490 508 7.56 mg/m3 0.4 900 >10,000 1.0 mg/m3

Iron 21.5 1201.3 1222.8 1100 210,000 211,000 777.28 mg/m3 30.9 696 >10,000 5.0 mg/m3

Copper 0.05 1.55 1.6 1.5 170 171.5 1.24 mg/m3 (0.05) ND 1.0 mg/m3

Chromium 0.02 0.68 0.7 0.88 100 100.88 O.49 mg/m3 (0.05) ND 0.5 mg/m3



October 22-23, 1997


OH(A)/IH OH(C)/IH


AB #11

Lead 0.001 0.03 0.031 (0.2) (0.2) (0.2) ND <0.5 ND 0.1 mg/m3

Arsenic 0.008 0.04 0.048 <0.9 <0.3 <0.9 ND <2.3 ND 2 µg/m3 (C)

Manganese 0.4 5.14 5.54 8.5 88 96.5 5.35 mg/m3 0.2 2000 >10,000 1.0 mg/m3

Iron 29.2 463.8 493 1000 40,000 41,000 411.3 mg/m3 13.0 2246 >10,000 5.0 mg/m3

Copper 0.07 0.77 0.84 1.0 22 23 0.79 mg/m3 <0.08 ND 1.0 mg/m3

Chromium 0.03 0.38 0.41 (0.3) 15 15 0.38 mg/m3 <0.5 ND 0.5 mg/m3

Notes:All Sample #s and times are the same as those described in Table 1 for the corresponding abrasive blaster individual identifier number. All reported values are time-weighted averageconcentrations in milligrams per cubic meter (mg/m3) except for the passive samples (mass only) and IH sample (micrograms per cubic meter [µg/m3]). All employees wore a half-mask air-purifying respirator with HEPA filter in addition to the blast hood.< = less thanND = Not determined() = values in parentheses indicate the contaminant concentration was between the analytical limit of detection (LOD) and the limit of quantification (LOQ).NA = Sample was not analyzedA = Filter Analysis OH = Outside Blast Hood SampleB = Larger size particulate fraction (loose bulk) removed from filter and analyzed separately P = “passive” sample, closed face filter, obtained outside Blast HoodC = Total (A + B) IH = Inside Blast Hood SampleAB # = Abrasive Worker Individual Identifier Number OH(C) minus P(C) = the concentration determined by subtracting the contaminant mass detected on the passive filter from the total contaminant mass detected on the outside the blast hoodsample. WPF = workplace protection factor: defined as the ratio of the measured contaminant concentration outside the respirator face piece to the contaminant concentration inside the respirator facepiece (OH-C/IH and OH=A/IH). The samples were taken simultaneously while the respirator was being properly worn and used during normal work activities.NC = The sample set was not compared because one OH sample was lost due to pump damage.


Table 4Avondale Shipyards: HETA 97-0260

Paired Bulk Sample Results - Steel Grit from Shot House. All Results in µg/g

Description As Pb Cr Cu Mn Fe

ACS DC ACS DC ACS DC ACS DC ACS DC ACS DC

1A/1B: South Pot, Recycle Grit 74.1 43 4.5 3 529.3 470 942.5 680 3529 2300 949K 106

2A/2B: South Side, Coarse Reject 49.1 40 65.8 29 519 640 1518 950 6909 3400 683K 800K

3A/3B: South Side, Fine Reject 30.2 16 223.4 190 408.9 320 1035 910 6486 5600 385K 360K

4A/4B: North Side, Recycle Grit 41.3 39 4.3 1.4 264 270 836 770 1104 2100 953K 990K

5A/5B: North Side, Coarse Reject 32.1 41 25.5 7.4 418.6 290 909.5 790 4607 2599 743K 870K

6A/6B: North Side, Fine Reject 16.1 12 35.2 71 463.5 270 1155 640 9703 7200 526K 320K

7A/7B: Inside Shot House Floor 41.7 46 6.5 1.5 464.6 240 791.5 810 2174 1700 958K 106

8A/8B: Virgin Shot - G40 SteelGrit

31.9 30 5.9 ND 149.1 ND 698.2 430 912 1200 962K 870K

ACS = NIOSH Analytical Chemistry Services (Analysis by Inductively Coupled Plasma EmissionSpectroscopy)

DC = Data Chem (Analysis by Atomic Absorption Spectroscopy)µg/g = microgram of contaminant per gram of sample, equivalent to part per million (ppm).No cadmium detected in either sample setAs = arsenicPb = leadCr = ChromiumCu = CopperMn = ManganeseFe = Iron


APPENDIX A: SAMPLING AND ANALYTICALMETHODOLOGY

Processes selected for monitoring were based on an assessment of employee work activities and controls utilized.Activities of concern noted by the HHE requesters were also targeted for sampling. The monitoring was conductedutilizing established analytical protocols (NIOSH analytical methods).1 Calibrated air sampling pumps wereattached to selected workers and connected, via tubing, to sample collection media placed in the employees'breathing zone. A primary standard was used to calibrate the air sampling pumps. Monitoring was conductedthroughout the employees' work-shift. After sample collection, the pumps were post-calibrated and the averageof the pre- and post-calibration flow rates were used to determine the sample volume. All air samples weresubmitted to the NIOSH contract laboratory (Data Chem, Salt Lake City, Utah) for analysis. Field blanks weresubmitted with the samples and all reported results were blank corrected. Specific sampling and analyticalmethods used during this survey were as follows:

Welding FumePersonal exposures to airborne welding fume were monitored using Gilian HFS 513A or Gil-Air sampling pumps.Flow rates of approximately 2 liters per minute (l/m) were used to obtain the samples. The samples were collectedon tared 37 millimeter (mm),5 micrometer (:m) pore size, poly-vinyl chloride (PVC) filters in the closed-facemode, and analyzed gravimetrically to determine the total welding fume concentration according to NIOSHMethod 0500. An element specific analysis was also conducted on the samples, according to NIOSH Method7300, to differentiate and quantify the following metal species: lead, iron, chromium, arsenic, manganese, andcopper. With this technique, the sample filters are microwave digested in an acid mixture, and analyzed with aregular inductively coupled plasma emission spectrometer (ICAP). Additionally, all samples found to benondetected for lead using the regular ICAP were reanalyzed using a trace ICAP. These reanalyses wereconducted to verify that the nondetected values for lead were not the result of the dilutions necessary to overcomethe high iron concentrations present on the samples.

Abrasive BlastingPersonal breathing zone (PBZ) monitoring during abrasive blasting activities was conducted to evaluate exposureto total particulate and the following metal species: lead, iron, chromium, arsenic, manganese, copper, using thesame methods as that described for welding fume. For each abrasive blaster monitored, samples were collectedin three locations: inside the blast hood, outside the blast hood, and a “passive” sample outside the blast hood.

The inside the blast hood samples were obtained by connecting the air sampling pump to the worker and attachingthe filter to the inside of the blast hood using a Helmet Sampling Adaptor (SKC, Inc., Cat.# 225-600) to positionthe sampling cassette adjacent the workers’ breathing zone. The pump was activated just prior to the workerdonning the blast hood and entering the Shot House. Sampling was conducted for the duration of the work shift.The outside the blast hood samples were collected by attaching the filter cassette to the abrasive blast shroud.Because of the anticipated high loading on the filters, the cassettes were changed out every 1 - 1.5 hours (wheneverthe worker exited the Shot House). Time-weighted average concentrations were calculated using the followingformula:


1. NIOSH [1994]. NIOSH manual of analytical methods, 4th ed. Eller, RM, ed. Cincinnati, OH: U.S.Department of Health and Human Services, Public Health Service, Centers for Disease Control andPrevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.

TWA (milligrams/cubic meter) = C1T1 + C2T2 + CnTn T1 + T2 + Tn

Where: C1T1 = concentration measured during sampling period T

The passive samples were collected by attaching a 4 inch length of Tygon tubing to a filter cassette containing atared 37 mm, 5 :m pore size poly vinyl filter. The tubing and cassette was then secured to the outside of theabrasive blast shroud and the inlet cap removed (closed face mode). The filter cassette was worn by the workerfor the duration of the work shift.

On both the passive and outside the hood samples, the larger size fraction (loose grit) was removed from the filterand analyzed (gravimetrically and elementally) separately. Although a rigorous definition and size range for thislarger particulate size fraction was not determined, the larger particles removed and analyzed separately arebelieved to consist primarily of rebound or inertia driven shot and not in a size range considered to present aninhalation hazard. For each filter portion analyzed from the outside the hood sample, TWA concentrations werecalculated. The two measurements were then combined to calculate the total concentration. Because no air wasdrawn through the passive monitor, only the total weight (milligrams) was reported.

Bulk SamplesEight steel grit bulk samples in duplicate were collected from the Shot House in wide-mouth polyethylenecontainers to determine the concentration of the following elements: lead, iron, arsenic, cadmium, chromium,copper, and manganese. One sample from each pair was shipped to the NIOSH contract laboratory (DataChem,Salt Lake City, Utah) and the companion sample shipped to the NIOSH laboratory (ACS) for analysis. The purposeof the paired sampling was to address potential analytical problems associated with quantifying low concentrationsof lead in a sample that is predominantly iron using ICAP as the analytical method. In addition to the steel gritsamples, a bulk sample of the mild steel used in the factory, and both components of a 2-part epoxy resin used asa pre-construction primer prior to welding and abrasive blasting were submitted to ACS for elemental analysis.At the NIOSH contract laboratory, an aliquot from each sample was digested and analyzed by graphite furnaceatomic absorption spectrometry (AAS). Because of high iron concentrations, some samples required dilutions upto 1000X. At ACS, an aliquot of each sample was analyzed by ICAP according to NIOSH Method #7300. Todetermine recovery data, Standard Reference Material 364 (high carbon steel) from the National Institute forStandards and Technology (NIST) was found to be the best available match to the samples. The air samples wereplaced on hold until the results of the bulk sampling were available.

References


APPENDIX B: CONTROL OF WELDING FUMETo reduce the hazard of welding fume exposures, the following hierarchy of controls should be considered:automation, substitution, isolation, ventilation.

! Partial or complete automation so the welder is less exposed to welding fumes.

! Implement process changes to limit hazards. For example, determine if different joining process other thanwelding can be used, if lower fume-producing welding processes, such as submerged arc welding or gastungsten arc welding (GTAW or TIG) are feasible; or if low-fume electrodes can be substituted for theelectrodes currently used.

! Isolate or enclose the welding process to limit the hazard to workers.

! Utilize ventilation to remove the fumes and gases from the welder’s breathing zone.

A number of ventilation systems are commercially available to help control fume emissions during weldingoperations. Local exhaust ventilation (LEV) controls capture the air contaminants directly at the point ofgeneration and are generally positioned no more than 12 inches away from the source. LEV systems are moreeffective than general ventilation systems since the air contaminants can be captured and removed before they canreach the welder’s breathing zone. However, the effectiveness of the LEV system is often dependent on how thewelder positions the hood; if the hood is placed too far from the welding operation it may not adequately capturethe air contaminants, depending on the capture velocity. LEV systems used during industrial welding operationscan include: fixed movable hoods, portable movable hoods, fume extraction guns, and, to some extent, canopyhoods.

Movable HoodsOSHA 29 CFR 1910.252 recommends that “(movable hoods) should be placed as near as practicable to the workbeing welded and provided with a rate of airflow sufficient to maintain a velocity in the direction of the hood of100 fpm in the zone of welding when the hood is at its most remote distance from the point of welding.” Tomaintain a capture velocity of 100 fpm, OSHA provides the following values when using a 3" wide, flanged hood.

OSHA GUIDELINES FOR MOVABLE HOOD AIRFLOW RATES

Distance from Arc to Hood (in) Airflow (cfm)

Duct Diameter (in)

4-6 150 3

6-8 275 3.5

8-10 425 4.5

10-12 600 5.5


The ACGIH Ventilation Manual also provides guidelines on the use of movable exhaust hoods for weldingoperations.1 The airflow rates suggested by ACGIH are more conservative than those recommended by OSHA.

ACGIH GUIDELINES FOR MOVABLE HOOD AIRFLOW RATES

Distance from Arc to Hood (in)

Plain DuctAirflow (cfm)

Flange or Cone HoodAirflow (cfm)

up to 6 335 250

6-9 755 560

9-12 1335 1000

Fume Extraction GunsFume extraction guns are high vacuum, low volume controls. Two types of fume extraction guns are available.One type of gun incorporates the ventilation directly into the gun design. Lines for the shielding gas and exhaustedair are encased in a large, single line leading from the gun. The second type of gun uses a conventional,nonventilated model with a suction attachment connected to the gun nozzle. On this model, the shielding gas andexhausted air lines remained separate. The type of gun used often depends on the welder’s personal preference.Welders who find the all-in-one fume extraction gun bulky and cumbersome may prefer to use a conventional gunwith the suction attachment. One manufacturer gives the following comparison of airflow rates for fume extractionguns and suction devices.2

APPROXIMATE AIRFLOW RATES FOR LEV SYSTEMS

Suction Device Approximate Airflow Requirement (cfm)

Fume Extraction Gun 20-60

Small Suction Hood 40-80

Large Suction Hood 80-160

Although local exhaust ventilation can be very efficient at reducing worker welding fume exposures, there aremany impediments to the successful implementation of this type of ventilation control in the shipbuilding industry:

(1) Controls must be usable in confined or enclosed spaces, or in awkward positions.(2) Controls must be usable by a mobile workforce and may require extensive reaches.(3) Controls must be able to be moved out of the way of overhead cranes and hoists when necessary.(4) Duct work for controls must be tough enough to endure misuse and abuse.(5) Controls must be able to effectively filter exhaust air before releasing it back into the welding area, or must

exhaust air to the outside (preferrable).(6) Controls must be flexible enough to adjust to changes in unit size and configuration, or changes in the

process layout.


1. ACGIH [1992]. Industrial ventilation: a manual of recommended practice. 21st Ed. Cincinnati, Ohio.American Conference of Governmental Industrial Hygienists.

2. Lincoln Electric [1994]. Lincoln Environmental Systems. High-Vacuum Solutions. Fume X-TractorTM

Products. Product Literature, E13.10. Cleveland, OH

There can be additional drawbacks to using the various types of local exhaust ventilated controls. For example,welders may resist using fume extraction guns if they consider them to be too cumbersome or if they believe theventilation is exhausting the shielding gas in addition to the fumes. Movable hoods are only effective if welderscontinually position the hood close to the point of fume generation. Portable ventilated units may be too large tomaneuver through the work in progress on the Factory floor.

If local exhaust ventilation controls cannot be implemented, general exhaust ventilation (GEV) controls should beconsidered. A drawback to a GEV system is that, although it may help to reduce overall fume levels in the facility,it may not have a significant impact on reducing the exposure levels of the welder. OSHA 29CFR1910.252recommends a minimum exhaust ventilation rate of 2000 cfm per welder when welding in a space of less than10,000 ft3 per welder, or when in a room with a ceiling height of less than 16 ft, or when in confined spaces orwhere the welding space contains structural barriers to the extent that they significantly obstruct cross ventilation.The ACGIH Ventilation Manual suggests the following general ventilation airflow rates: (1) for open areas wherewelding fume can rise away from the breathing zone the airflow required (cfm) = 800 x lb/hour of rod/wire used;(2) for enclosed areas or positions where fume does not readily escape the breathing zone the airflow required (cfm)= 1600 x lb/hour of rod/wire used. Examples of general exhaust ventilation controls include: suspended airfiltration units and roof ventilators.

Other Welding Fume ControlsIn addition to engineering controls, other factors such as work practices, personal protective equipment, andadministrative controls should be investigated to help reduce worker exposures to welding fumes. Examples ofwork practices that may help to lower worker fume exposures include: educating welders to keep their heads outof the weld plume and to remain aware of air currents to ensure welding is performed upwind of the fumes as muchas possible. Examples of personal protective equipment include: proper use of respirators, use of weldingglasses/goggles/hoods by welders and workers in the vicinity, and availability of welding screens to place aroundweld operations. Examples of administrative controls include: job rotation to limit welders’ exposures, trainingand education of welders on hazards and controls associated with their jobs, ensuring welders use ventilation andother control measures supplied to them.

References

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